1. Field of the Invention
The present invention relates to magnetic disk drives, and more particularly, to a method for preventing radial error propagation during self-servowriting of tracks on a magnetic disk of a disk drive.
2. Description of the Prior Art and Related Information
The writing of servotrack information on a magnetic disk medium is a critical process in the manufacture of a disk drive. Conventionally, servotrack information is written with a specialized servowriting instrument mounted on a large granite block to minimize external vibration effects. Increasing track densities and decreasing disk-drive size has led to the investigation of self servowriting techniques. One issue confronting the use of self servowriting is track-to-track or radial error propagation and amplification of written-in errors and imperfections with respect to a perfectly circular track.
U.S. Pat. No. 5,907,447 to Yarmchuk et al. describes reduction of radial error propagation by generating a correction signal using a filter applied to a position error signal (PES) to reduce a closed-loop response of a track-following servo loop to less than unity at frequencies equal to integer multiples of the disk rotation frequency. While permitting implementation of self-servowriting with reduced radial error propagation, the PES filtering technique of the Yarmchuk patent fails to readily support increasingly aggressive track densities.
Accordingly, there exists a need for a technique for preventing radial error propagation during self-servo writing of tracks on a magnetic disk in a disk drive without unnecessarily increasing manufacturing costs or significantly impacting manufacturing throughput. The present invention satisfies these needs.